1. Field of the Invention
The present invention relates to a method of controlling communication between a plurality of devices such as personal computers or printers connected to a network, and, in particular, relates to a method of communication control in a network wherein communication is possible under a plurality of protocols.
2. Description of the Related Art
Currently, LAN (Local Area Network) environments are common as a mode of effecting network connection of devices such as personal computers and/or printers. In such an LAN environment, for example TCP/IP is employed as the communication protocol between devices. Under TCP/IP, respective IP addresses are allocated to each device. Thus, when data is transmitted using TCP/IP, the IP address of the destination device (for example printer) must be designated, so it is necessary that the originating device (for example personal computer) should acquire and store beforehand the IP addresses of destination devices.
However, these IP addresses can be altered by operation by the operator. Furthermore, in an environment in which IP addresses are automatically allocated by DHCP operation, the IP addresses of the devices are not fixed. Thus, there is the problem that, when the IP address of a destination device is altered, communication with the destination device becomes impossible, since a wrong IP address is specified for the originating device as the IP address of the destination device.
In this situation, in order to recommence communication, the operator had to find the IP address of the destination device by a manual operation and correct the IP address that is stored beforehand-in the originating device; this operation was extremely troublesome.
An object of the present invention is therefore to provide a communication control method whereby, when the IP address of a destination device is altered, communication is recommenced by automatically correcting the IP address stored in the originating device.
In order to achieve the above object, according to the present invention, when communication utilizing a first protocol that is normally employed in a network wherein communication can be performed by a plurality of protocols fails, the cause of failure is examined by communication using a second protocol, and communication is recommenced utilizing the first protocol by automatically performing repair. Consequently, communication using the first protocol can be recommenced without interruption of communication, without requiring a correction operation by manual action by the operator.
Preferably, in a method of communication control in a network wherein communication is possible using a plurality of protocols, a first communication control method according to the present invention for achieving the above object comprises the steps of: commencing communication using a first protocol; examining the set condition of information for the first protocol by communication using a second protocol; if there is abnormality in the set condition, repairing this; and if there has been a failure in communication using the first protocol, after the repairing step, recommencing communication using the first protocol.
Also, in a method of communication control in a network wherein communication is possible using a plurality of protocols, a second communication control method according to the present invention for achieving the above object comprises the steps of: commencing communication using a first protocol; examining the set condition of information for the first protocol by communication using a second protocol; if there is abnormality in the set condition, repairing this; and if there has been a failure in communication using the first protocol, substituting communication utilizing a third protocol for communication using the first protocol.
In the first and second method, for example, where communication using the first protocol is communication between a first device and a second device connected to a network, in the examining step, information for the first protocol that is set in a second device is acquired by the first device, and, in the repairing step, if the acquired information and the information for the first protocol that is set in the first device do not agree, the information for the first protocol that is set in the first device is updated to the acquired information.
Also, the information for the first protocol includes, for example, address information in the first protocol of the second device. Furthermore, the first device stores beforehand the MAC address of the second device, and the address information of the second device is acquired by retrieval using the MAC address of the second device.
Furthermore, according to the present invention, there are provided a communication control device that executes the above communication control method and a recording medium that stores a program whereby the above communication control method is executed.